Misdiagnosed Gestational Diabetes

Amber
So I'm 28w3d. Last Thursday i took the 3 hr test and on Friday they called to tell me I failed 3 of the 4 test. I don't know what the numbers were. 
On my first test I failed with a 163. I feel like I've been misdiagnosed. With the first test I didn't know that after drink the glucola that you can't drink anything, so I had about an entire bottle of water. With the 3 hr test. My appointment was in the morning, the doctor told me to not eat after midnight, she didn't tell me I needed about 12 hours of fasting before the 3 hr test though. I ate before midnight and then had the test in the morning, so not many hours went by before the test. Well needless to say they diagnosed me with GD and for the last few days I've been checking my blood 4x a day and my numbers have been perfect. I haven't changed much with my diet. I'm snacking more than I was before because I wouldn't skip meals but with me checking my blood I've been eating more to make sure I do at certain times and can do the finger prick in 2hrs. Today I had a Large coke and two slices of pepperoni pizza and 2 hrs later when I tested my blood it was the highest it's been at a whopping 120.....which isn't high at all. I feel like I've been misdiagnosed. I failed the tests because I didn't do what I should have. I was misinformed. I'm sure lots of people complain to their doctors and I don't want to seem like I'm in denial but...with no change to my diet and everything looking extremely normal, I don't see how I could have this. I've read lots of websites and blogs about others who thought they were misdiagnosed but no one ever gave follow ups. Has anyone else experienced this? And things changed later or the doctor agreed?
 I go back to the doctor next week and I plan on talking with her about it, I just don't want her to think I've changed my diet and that's why numbers are different. I really believe it was wrong. ALSO. I've had no symptoms and every time I go to dr. baby nor I is overweight. We had an ultrasound to measure everything with baby last week because my belly was a little larger than it was suppose to be and he was perfect and this week belly is back to normal measurements.....
Help, this has me stressed out! I know that it doesn't hurt to make sure you're eating healthy but some of it is ridiculous and pricking ur finger 4x a day is tedious, especially if I don't really have GD. I don't want to have any unnecessary stress for the next three months because I think I'm making my baby fat or harming him.